Instantiator: Do not load items when inactive

Instantiator would react to model changes even when inactive, causing
instances to be errorneously created.
We simply skip doing anything when inactive, as setting the Instantiator
to active later will trigger a full regenaration anyway.

Pick-to: 6.2 5.15
Fixes: QTBUG-86453
Fixes: QTBUG-88331
Change-Id: Ia5fd916bbd591d5fc72c550424b1a53a142c2fa8
Reviewed-by: Maximilian Goldstein <max.goldstein@qt.io>
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

3 files changed, 61 insertions, 1 deletions

diff --git a/src/qmlmodels/qqmlinstantiator.cpp b/src/qmlmodels/qqmlinstantiator.cpp
index 3b663badf5..cb7ca1126c 100644
--- a/src/qmlmodels/qqmlinstantiator.cpp
+++ b/src/qmlmodels/qqmlinstantiator.cpp
@@ -147,7 +147,7 @@ void QQmlInstantiatorPrivate::_q_modelUpdated(const QQmlChangeSet &changeSet, bo
 {
     Q_Q(QQmlInstantiator);
 
-    if (!componentComplete || effectiveReset)
+    if (!componentComplete || effectiveReset || !active)
         return;
 
     if (reset) {
diff --git a/tests/auto/qml/qqmlinstantiator/data/activeModelChangeInteraction.qml b/tests/auto/qml/qqmlinstantiator/data/activeModelChangeInteraction.qml
new file mode 100644
index 0000000000..2797566ad2
--- /dev/null
+++ b/tests/auto/qml/qqmlinstantiator/data/activeModelChangeInteraction.qml
@@ -0,0 +1,39 @@
+import QtQuick 2.15
+import QtQml.Models 2.15
+
+Item {
+    id: root
+    property int instanceCount: 0
+    property alias active: instantiator.active
+
+    ListModel {
+        id: listmodel
+
+        dynamicRoles: true
+    }
+
+    Component.onCompleted: {
+        listmodel.insert(listmodel.count, {name: "one"})
+        listmodel.insert(listmodel.count, {name: "two"})
+        listmodel.insert(listmodel.count, {name: "three"})
+    }
+
+    Instantiator {
+        id: instantiator
+
+        active: false
+
+        model: listmodel
+
+        delegate: Text {
+            width: 100
+            height: 20
+
+            text: name
+
+            Component.onCompleted: ++root.instanceCount
+        }
+
+    }
+}
+
diff --git a/tests/auto/qml/qqmlinstantiator/tst_qqmlinstantiator.cpp b/tests/auto/qml/qqmlinstantiator/tst_qqmlinstantiator.cpp
index dc0365c5cf..4c6c84a9d2 100644
--- a/tests/auto/qml/qqmlinstantiator/tst_qqmlinstantiator.cpp
+++ b/tests/auto/qml/qqmlinstantiator/tst_qqmlinstantiator.cpp
@@ -50,6 +50,7 @@ private slots:
     void createMultiple();
     void stringModel();
     void activeProperty();
+    void activeModelChangeInteraction();
     void intModelChange();
     void createAndRemove();
 
@@ -161,6 +162,26 @@ void tst_qqmlinstantiator::activeProperty()
     QCOMPARE(object->property("idx").toInt(), 0);
 }
 
+void tst_qqmlinstantiator::activeModelChangeInteraction()
+{
+    QQmlEngine engine;
+    QQmlComponent component(&engine, testFileUrl("activeModelChangeInteraction.qml"));
+    QScopedPointer<QObject> root(component.create());
+    QVERIFY(root);
+
+    // If the instantiator is inactive, a model change does not lead to items being loaded
+    bool ok = false;
+    int count = root->property("instanceCount").toInt(&ok);
+    QVERIFY(ok);
+    QCOMPARE(count, 0);
+
+    // When turning the instantiator active, it will however reflect the model
+    root->setProperty("active", true);
+    count = root->property("instanceCount").toInt(&ok);
+    QVERIFY(ok);
+    QCOMPARE(count, 3);
+}
+
 void tst_qqmlinstantiator::intModelChange()
 {
     QQmlEngine engine;